A Very Deceiving Night: Thermal Inversion

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Further analysis of previously unseen log books and Greenwich Mean Noon Observations from more than 75 ships which passed through the area where the Titanic sank, between the 5th and the 25th of April 1912 revealed a more detailed picture.

Example Greenwich Mean Noon Observations form from the Almerian, showing her 15th April 1912 8.38am reading of 31 degrees Fahrenheit water temperature at 41.48N, 50.24W, when she was “In among pack-ice”:

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Plotting all of the air and sea temperatures and positional data and times from these records revealed that, two days before the accident, Titanic’s freezing wreck site had been much warmer.

At 6pm on 12th April 1912, the log of the eastbound German steamer, Alster, shows she was only 3 miles southwest of Titanic’s eventual wreck site when she recorded a sea temperature of 5⁰C; and an hour later, at 7pm, when she was only about 8 miles east of Titanic’s wreck site, she recorded a sea temperature of 12.6⁰C.

Combining all the data from all these ships, reveals that the freezing Labrador Current had only recently flowed through the area like a river:

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Thermal map of Titanic’s wreck site compiled using the log book and Greenwich Mean Noon Observations forms data from more than 75 ships which passed through the area, 5th – 25th April 1912

The warm waters of the Gulf Stream had previously warmed the air column above Titanic’s eventual wreck site to about 12 degrees Celsius, but now the freezing Labrador Current had flowed into this normally warm area of the sea, under-running the warm air and causing the air column at Titanic’s wreck site to cool rapidly, from the bottom up, as the air near the surface of the sea dissipated its heat into the freezing water flowing south in the Labrador Current.  This created a steep thermal inversion at Titanic’s wreck site, with stratified layers of cold air lying below layers of much warmer air, higher up.  As Lightoller noticed, Titanic had begun to head into this thermal inversion at about 7pm on the evening of her fatal collision:

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In the above diagram, we can see how Titanic was leaving the warmer air, higher and higher up, as she headed deeper into the thermal inversion.  The Paula and the Trautenfels are the last two vessels we have found complete log books for who went through the area of Titanic’s wreck site, in daylight, before Titanic’s collision.

Graph showing Trautenfels water and air temperature readings at Titanic’s eventual wreck site, early in the morning on 14th April 1912. Temperature is on the Y-axis; time, date and distance east and west from Titanic’s wreck site is on the X-axis:

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In the inversion the air temperature at deck height is about two degrees warmer than the sea, less than 40 feet below.  This indicates a strong thermal inversion, sufficient to cause miraging. But if Trautenfels had been to read the air above deck height it would have been even warmer, and high above the ship the air would still have been at 13 degrees Celsius, which is the temperature it had previously been heated to by the warm waters of Gulf Stream on either side, before the freezing Labrador Current arrived on the scene and began cooling the air, from the bottom up.

14 hours later, when the Californian arrived on the scene the freezing water of the Labrador current would have had the effect of cooling the air at deck height to the same temperature as the sea, so no inversion could be measured from the deck, but there would still be a 13 degree inversion higher up.  This explains why the temperature readings of the Californian, who remained near Titanic’s wreck site all that night, recorded similar air and sea temperatures.  The failure to understand that there could still be a strong thermal inversion present, higher up, in this situation is one of the main reasons why the strong thermal inversion at Titanic’s wreck site has not been discovered until now:

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Thermal inversions cause abnormal refraction or miraging, where light bends abnormally, and are common in the Grand Banks area of the North Atlantic where Titanic sank. Many were recorded by British scientist G. I. Taylor, in his 1913 expedition to the area on board the research vessel Scotia.

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British scientist G.I. Taylor

Taylor is sometimes known as “The father of meteorology” and he was sent to Titanic’s wreck site after the disaster, together with a group of other scientists, to research the causes of fog on the Grand Banks. Here G. I. Taylor flew kites into the air column, fitted with altimeters and thermometers.  The graph below shows the results of a typical ascent, the air immediately above the cold sea being only 4.5 degrees Celsius, but rising to 9 degrees Celsius by 100 metres and more than 12 degrees Celsius by 300 metres:

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G.I. Taylor 1913 Temperature-height diagram from his Grand Banks kite ascents

In these conditions, G. I. Taylor noticed that the smoke from the funnel of the Scotia hung in stratified layers, because it could rise through the colder air near the sea, but could not rise up higher, into the much warmer and therefore less dense air higher up.  He photographed this phenomenon and published it in his 1917 essay “The Formation of Fog and Mist”:

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1913 photograph by G. I. Taylor of flat-topped smoke from the steamship Scotia, on the Grand Banks of Newfoundland

Taylor said: “When I first noticed these streaks [of smoke], I used to think that they were formed on days when there was no wind at all, and that they marked the position in the stationary atmosphere through which the steamer’s funnel had passed. Later, however, in 1913 I had an opportunity of studying these streaks under exceptionally favourable conditions and came to a different conclusion. At that time I was cruising on the whaling ship Scotia over the Banks of Newfoundland and off the coast of Labrador.  In these regions the sea consists of water which has come down out of Baffin Bay with the Arctic current. It is therefore exceptionally cold. The air, on the other hand, is frequently from the West and blows off the mainland of Canada which is very warm during the later months of summer [or from the warmer waters of the Gulf Stream nearby]. Under these conditions an inversion of temperature close to the surface of the sea is of very frequent occurrence.”

In his Report, Taylor stated:

“The ideal conditions for the formation of a large temperature gradient are –

  1. A rapid change in the sea temperature along the air’s path.
  2. A large range in temperature.
  3. A small wind velocity, because the eddy motion seems to increase rapidly with wind velocity.”

And this is exactly the conditions we find at Titanic’s wreck site; a sharp boundary between warm and cold water, and very still air at the wreck site:

S.S. Paula, April 14th 1912, 41.56N 50.03W: “After 2pm no wind, calm sea, fine weather.”

I hope by blogging chapters from my book, A Very Deceiving Night, it will contribute to the ongoing discussions regarding the atmospheric conditions on the night of the tragedy and the true causes of the disaster. At the moment, the book is only available as an e-book. If you wish to purchase it then you can do so in Amazon Kindle format here and other formats, including Apple, Kobo and Nook, here. Thank you.

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